We have identified a cell cycle delay in Saccharomyces cerevisiae RNase MRP mutants. Mutants delay with large budded cells, dumbbell-shaped nuclei, and extended spindles characteristic of "exit from mitosis" mutants. In accord with this, a RNase MRP mutation can be suppressed by overexpressing the polo-like kinase CDC5 or by deleting the B-type cyclin CLB1, without restoring the MRP-dependent r...

The x-ray crystal structure of a 417-nt ribonuclease P RNA from Bacillus stearothermophilus was solved to 3.3-A resolution. This RNA enzyme is constructed from a number of coaxially stacked helical domains joined together by local and long-range interactions. These helical domains are arranged to form a remarkably flat surface, which is implicated by a wealth of biochemical data in the binding ...

RNase P is the enzyme that removes 5' extensions from tRNA precursors. With its diversity of enzyme forms-either protein- or RNA-based, ranging from single polypeptides to multi-subunit ribonucleoproteins-the RNase P enzyme family represents a unique model system to compare the evolution of enzymatic mechanisms. Here we present a comprehensive study of substrate recognition and cleavage-site se...

g]ycoproteins and their amino acid compesitions are significantly different from that of RNase Le2. In addition to these enzyines, a guanylic acid-specific RNase with a molecular mass 13 kDa was panially purified. Since RNase Le2, which has yery similar IVLterminat sequence to RNase Le 37 and RNase Le 45, was not excreted from the mycelia, the analysis of the structures of these two excreted RN...

Escherichia coli RNase R, a 3 3 5 exoribonuclease homologous to RNase II, was overexpressed and purified to near homogeneity in its native untagged form by a rapid procedure. The purified enzyme was free of nucleic acid. It migrated upon gel filtration chromatography as a monomer with an apparent molecular mass of 95 kDa, in close agreement with its expected size based on the sequence of the rn...

The RNA-protein subunit assembly of nuclear RNase P was investigated by specific isolation and characterization of the precursor and mature forms of RNase P using an RNA affinity ligand. Pre-RNase P was as active in pre-tRNA cleavage as mature RNase P, although it contained only seven of the nine proteins found in mature RNase P. Pop3p and Rpr2p were not required for maturation of the RPR1 RNA ...

The objective of this investigation is to examine the potential for using plant ribonuclease P (RNase P) as a tool for cleaving target mRNAs and thereby disrupting gene expression in plants. RNase P is a ubiquitous ribonucleoprotein that is uniquely responsible for the 59 maturation of nearly sixty-odd precursor tRNAs (ptRNAs) in prokaryotes and eukaryotes (Fig. 1A; Altman and Kirsebom, 1999; F...

Contact-dependent growth inhibition (CDI) is an important mechanism of inter-bacterial competition found in many Gram-negative pathogens. CDI+ cells express cell-surface CdiA proteins that bind neighboring bacteria and deliver C-terminal toxin domains (CdiA-CT) to inhibit target-cell growth. CDI+ bacteria also produce CdiI immunity proteins, which specifically neutralize cognate CdiA-CT toxins ...

Precursor-messenger RNA (pre-mRNA) splicing encompasses two sequential transesterification reactions in distinct active sites of the spliceosome that are transiently established by the interplay of small nuclear (sn) RNAs and spliceosomal proteins. Protein Prp8 is an active site component but the molecular mechanisms, by which it might facilitate splicing catalysis, are unknown. We have determi...